The Sampling and Data Management core will conduct random sampling using the selected database. It will assume multiple functions pursuant to its central task of assuring effective and valid collection, processing, and utilization of study data. It will ensure consistent study methodology and proper execution across sites. It will also develop and service the communications network of the study, involving the online discussion bulletin board and the central database containing all of the analytic values derived from the study subjects, from both the questionnaires and laboratory data. This central database will feature a user-friendly, secure, web-based interface for study scientists, who will be able to enter their own data, view their own data as well as data generated by others, and to perform basic statistical analyses, including correlational analysis across domains, in real time. The Sampling and Data Management Core will provide support to the Recruitment and Clinical Testing Core in the initial phases of subject recruitment. The Sampling and Data Management Core will take responsibility for security issues involving the study subjects. It will also consult with and service all of the participating scientists to enhance the speed and quality of the data analyses and publications from the study. It will provide statistical and epidemiologic analytic support, will consult with all investigators in the early stages of the study, will support preparation of manuscripts from the study, and ensure that methods appropriate for the study design and database are used. It will also provide data verification of all tables prior to publication. Additionally, the Sampling and Data Management Core will enhance the quality of its epidemiologic procedures by evaluating how representative the use of the Medicare Beneficiary Enrollment file and Louisiana Voters Registration file is compared to the Drivers License/Personal Identification Card file. It will also conduct data verification of self-reported age in this study.